I searched the forum for the quality of the bokeh, and find a tread about bokeh from different fast Canon lenses. However - my question is - could different sizes of the sensor affect the end result how the quality of the bokeh will appear in the photo? The quality of bokeh in for example flower-images has made me interested and open my eyes for the right use of bokeh in order to create a photo that will be a complete in relation between sharpness and bokeh. Maybe here is others who has already dug into this subject much more profoundly and solidly?

For example can 5DMKII vs 5DMKIII vs 1DX produce slightly different character of how the bokeh will be formed in the photo when comparing the three full-format-sensors - due to the different mega-pixel-numbers?

Is the bokeh from an APS-C DSLR different in quality from the look from a full-frame DSLR´s?

Is the bokeh produced by the super-tele-lenses the most soft-edged, even with the quite "poor" MFD ((Minimum Focus Distance)?

(How about using many Extension Tubes, how many have you tested to stack when using for example the EF300/500/600mm, in order to not get vignetting? And last q - will the use of an additional and different Extender affect the bokeh in some way by prolonging the focal-lenght- when using either the APS-C vs full-frame sensor DSLR?

I would appreciate if someone maybe happens to have some experience of the bokeh result that you value and are satisfied with!

Wishing you all happy shootings!

//C

PS. The photo is with full-frame 5DMKII with EF100mm f/2.8L IS USM @ f/2.8 and the yellowish flowers are Rudbeckia which is an ancient flower named after Carl von Linné professor Olof Rudbeck Jr in Uppsala Sweden and the blue is a field of Cornflower, Bachelors button, Bluebottle, Boutonniere flower, Hurtsickle, or Cyani flower.

For example can 5DMKII vs 5DMKIII vs 1DX produce slightly different character of how the bokeh will be formed in the photo when comparing the three full-format-sensors - due to the different mega-pixel-numbers?

Possibly, but if so, it would be a very subtle difference, and likely only evident in some shots.

Is the bokeh from an APS-C DSLR different in quality from the look from a full-frame DSLR´s?

It can be. In some cases, the bokeh is better with an APS-C sensor, assuming you're using an EF (not EF-S) lens. Lens vignetting results in the bokeh of highlights at the edges of the frame having a 'cat's-eye' appearance instead of the more desirable round appearance, and since an APS-C sensor crops away the edges, the vignetting is less and the bokeh at the frame edges is better.

Is the bokeh produced by the super-tele-lenses the most soft-edged, even with the quite "poor" MFD ((Minimum Focus Distance)?

Not really. The supertele lenses are really optimized for sharpness. Lens design is all about tradeoffs. One lens known for particularly good bokeh (often described as 'creamy') is the 50mm f/1.2L. That lens is optimized for bokeh, and the way that's done is to undercorrect for speherical aberration in the lens design. When you do that, you get better bokeh, at the cost of a loss of some sharpness (and some focus shift, too).

In my opinion bokeh is produced by exposure (light waves under specific angles) and lens design (set of lens elements that pass through the light). Sensor is responsible for capturing the light and that's all.

In my opinion bokeh is produced by exposure (light waves under specific angles) and lens design (set of lens elements that pass through the light). Sensor is responsible for capturing the light and that's all.

But what about the different sensor size + distance from the lens, as I understand it the f-stop comparison needs to be adjusted from APS-C to FF, so perhaps this explains why the Bokeh on a crop may appear better at say f2.8, but using the same lens on a FF a direct like-for-like comparison would require a smaller aperture to get the same field of view...so really need to compare bokeh by adjusting aperture first??

When you say field of view I think of the width of the angle. I would rather say that a like-for-like comparison would require a smaller aperture to get the same depth of field...

As for the relationship between bokeh and sensor size, they key point must be that with a larger sensor you get more space for bokeh in your picture. True, at the edges on FF bokeh could be considered to degrade somewhat, compared to an EF lens on a crop body (since the not-perfectly-circular bokeh will be cropped out), but still, I would argue that the quality of the bokeh benefits from a larger sensor. Why? Because the larger the sensor, the longer the focal length you employ for any certain field of view. Case in point: It should be easier to design a 35mm lens for full frame than a 17,5mm lens for micro four thirds that enables pleasant bokeh, since the latter lens will be more of a wide angle design. Am I wrong?

In my opinion bokeh is produced by exposure (light waves under specific angles) and lens design (set of lens elements that pass through the light). Sensor is responsible for capturing the light and that's all.

But what about the different sensor size + distance from the lens, as I understand it the f-stop comparison needs to be adjusted from APS-C to FF, so perhaps this explains why the Bokeh on a crop may appear better at say f2.8, but using the same lens on a FF a direct like-for-like comparison would require a smaller aperture to get the same field of view...so really need to compare bokeh by adjusting aperture first??

edit: so +1 on the angles point

Sorry, I've accepted aperture setting and sensor size as not relevant to my message as it is something pre-set depending to the subject we're shooting. So I was focused on things we don't usually take into account And you don't need to wait for an answer from me "which aperture and sensor size I'd choose?", full frame and fast prime do their job better than anything else for my shooting style

Distance from subject in focus to subject out of focus affects angles under which light from subject and background / foreground is being projected on the sensor, so I was mentioning only 2 most interesting parts:

Is the bokeh from an APS-C DSLR different in quality from the look from a full-frame DSLR´s?

It can be. In some cases, the bokeh is better with an APS-C sensor, assuming you're using an EF (not EF-S) lens. Lens vignetting results in the bokeh of highlights at the edges of the frame having a 'cat's-eye' appearance instead of the more desirable round appearance, and since an APS-C sensor crops away the edges, the vignetting is less and the bokeh at the frame edges is better.

It really is apple vs oranges, since the crop sensor is going to have a different DOF comparing the two would be difficult.I think the opposite from experience, the full frame is better. Because DOF and distance are a big factor, my preference may be because the apples are at the location that I want them to be more with the FF than the oranges are where I want them with the crop sensor.

...since the crop sensor is going to have a different DOF comparing the two would be difficult.

Of course, but bokeh is quality, not quantity.

The 100-400's bokeh looks jittery on either sensor format. The 70-200 II bokeh is much smoother on both formats, but on FF wide open there is definite cat's-eye bokeh at the edges, not seen on APS-C. All of that can easily be seen despite the difference in DoF for the same framing.

...since the crop sensor is going to have a different DOF comparing the two would be difficult.

Of course, but bokeh is quality, not quantity.

The 100-400's bokeh looks jittery on either sensor format. The 70-200 II bokeh is much smoother on both formats, but on FF wide open there is definite cat's-eye bokeh at the edges, not seen on APS-C. All of that can easily be seen despite the difference in DoF for the same framing.

To me it was a quality call, look at it and it felt good or not. Of all the things I pixel peep, I am not sure I ever have bokeh. Maybe I should, it just always seemed I prefered the FF bokeh and I really haven't thought about it.....till now.

Not really. The supertele lenses are really optimized for sharpness. Lens design is all about tradeoffs. One lens known for particularly good bokeh (often described as 'creamy') is the 50mm f/1.2L. That lens is optimized for bokeh, and the way that's done is to undercorrect for speherical aberration in the lens design. When you do that, you get better bokeh, at the cost of a loss of some sharpness (and some focus shift, too).

without going into lens technicals I don't entirely understand I DO agree with this point.

I normally like very sharp lenses with very little CA. That tends to require special types of elements and aspherical correction elements in the lens. This often results in lenses with poorer bokeh, tho they may have really nice flat field performance, great sharpness and low CA.

I will often choose a lens that has no aspherical elements in it when I want one that will give me smoother, more pleasing looking bokeh for a shot. For the most part, this works. Old primes, if you can live with whatever their shortcomings may be, are sometimes good for this. These lenses will often have a lot of CA and coma though, which can either add or subtract from the overall image effect.

OTOH, there are many cheap modern consumer zooms and many perform better than some old primes and are far more plentiful and compatible with modern cameras. I've got some used ones for as little as $100 that perform beautifully; acceptable sharpness of focussed subject and creamy smooth bokeh. (nikon 55-200mm VR comes to mind) You can buy a lot of them to experiment with for the price of a used 50/1.2 L !

More complex modern zooms can be hit-and-miss. Even within the same lens!My 70-200 f/2.8 L IS II for example. I haven't cataloged where it occurs but I know it does. At certain focal lengths and apertures the bokeh on this lens is horrible! But that only occurs in some situations over a very finite set of settings. It actually provides reasonably decent bokeh most of the time.

And of course, the bigger the sensor, the more ability you have to generate out of focus areas and bokeh.

Tilt-shift lenses can be put to work too if you have the budget for them.

Bokeh quality depends on the lens, no the sensor.What full frame gives you is MORE bokeh, not better bokeh (i.e. DoF is shallower).

Now, you can use this advantage to get BETTER bokeh, if you don't need MORE bokeh.

Say you have a 50mm f/1.4 and a 85mm f/1.4, both with similar bokeh quality, the first one on an APS-C camera, the second one on a full frame camera. You'll get a very similar field of view with both systems, but DoF will be shallower in the full frame system: you have MORE bokeh.Now, say you don't actually need a shallower depth of field: you want the background to be somewhat defined, just blurred in a more pleasing way. On your full frame system, you have to set aperture to f/2.2, and ISO to 800 instead of 320, and you'll have the same field of view, depth of field, and exposure, on both systems.

And, chances are, you'll have BETTER bokeh on the full frame system: BOKEH QUALITY SUFFERS AT FULL APERTURE. Most people don't usually notice, because more bokeh tends to trump better bokeh, but most of the lenses I've tested show better bokeh quality when closed down a bit:http://www.similaar.com/foto/lenstests/bokehtests.html(notice that at full aperture most lenses show a green or white halo around the specular highlights, and a tad more "nervousness" in the OOF area on the left side of the target)

actually i think the 'quality' of the bokeh is more down to the quantity and shape of the blades in the aperture... i.e. more blades a rounder bokeh... a fun thing to do is to cut holes of various shapes out of card and hold over the lens to give different shaped bokeh...

actually i think the 'quality' of the bokeh is more down to the quantity and shape of the blades in the aperture... i.e. more blades a rounder bokeh... a fun thing to do is to cut holes of various shapes out of card and hold over the lens to give different shaped bokeh...

The quantity and shape of the aperture blades will impact the shape of out-of-focus highlights - hence the pentagonal highlights from the nifty fifty, because it has 5 aperture blades. The "smoothness" of the blur is affected more by the optical design. Here you will see factors like whether the bokeh is smooth (e.g. 85mm f/1.2) or perhaps more "nervous" (like the 24-105mm f/4 can be). Other characteristics which have also been mentioned include "cats eyes" (in the out-of-focus highlights nearer the edge of the frame) and "onion rings" at the edges of highlights.Some lenses also differ in the quality of the background blur relative to the foreground blur. For instance, the 85mm f/1.2 is well-known for not only delivering a very creamy background blur, but also a very smooth foreground blur. - Many lenses do not do so well in terms of the quality of their foreground blur (which tends, generally to be less of an issue than background blur).